1. Field of the Invention
The inventions disclosed and taught herein relate generally to solenoids; and more specifically relate to methods of encapsulating solenoid coils.
2. Description of the Related Art
U.S. Pat. No. 4,284,312 discloses a “sealing type electrical connector with mating housing portions configured to inhibit undesirable seepage of water or other contaminates into its interior which would be detrimental. A first housing is formed of flexible, molded elastomeric material which is relatively soft. A second housing is molded of rigid thermoplastic material. Each housing includes a tubular outer wall with closed and open ends defining a hollow interior therebetween. The housing members each also include an inner plug portion integrally formed therewith and spaced inward from the tubular outer wall portion, each having electrical contact makers molded therein. The tubular wall of one housing member has an inner diameter slightly larger than the outer diameter of the tubular wall of the other housing member so that the members are assembled with the one member overlying the outer wall of the other member. Circumferentially extended sealing ribs on the member of elastomeric material are engaged by the other member and compressed in the space therebetween to prevent passage of water between the housing members and into the interior.”
U.S. Pat. No. 4,679,767 discloses a “solenoid arrangement including a coil of electrically conductive wire and a yoke of magnetic material surrounding the coil. The coil is completely encapsulated by a thermosetting resin, the resin being located between the coil and the yoke, and the yoke being encapsulated by a thermoplastic resin. Preferably, the thermosetting resin is an epoxy resin, and the thermoplastic resin is nylon. The yoke includes a side wall extending around the entire periphery of the coil, a top wall, and a bottom wall, the side, top, and bottom walls forming a box-like housing which substantially completely encloses the coil. A stationary armature extends from the top wall of the yoke into the center of the spool upon which the coil is wound, and a sleeve for accommodating a core tube extends from the bottom wall into the center of the spool.”
U.S. Pat. No. 4,683,454 discloses a “solenoid actuator including a coil of electrically conductive wire, a yoke of magnetic material surrounding the coil, and a non-electrically and non-magnetically conductive material encapsulating the coil and yoke. A pair of terminals connected to the ends of the coil project outwardly beyond an exterior surface of the encapsulation. Any of a variety of electrical connection modules is adapted to receive the coil terminals and electrically connect them to standard electrical connectors projecting from the module. Different modules have different forms of standard electrical connectors, so that regardless of the type of connector available at the source of electric power, a suitable module can be connected to the encapsulated coil for cooperation with the power source connector. The body of each module is formed of resilient material so that when the module is tightly attached to the coil encapsulation, a seal is formed completely surrounding the coil terminals. Particular modules may incorporate rectifiers, time delay circuits, power-enhancing circuits, and radio controlled switches.”
U.S. Pat. No. 6,175,083 discloses a “sealing mechanism is provided to seal a lead from a closed cavity of an apparatus. The sealing mechanism includes a mounting portion sealingly connected to the apparatus, a cap member having a recess defined therein with an elastomeric grommet compressively disposed in the recess. The elastomeric grommet has a passageway defined therethrough for the lead from the closed cavity to past through. The compressive forces induced into the elastomeric grommet applies a compressive force on the lead to provide a seal. The cap member is sealingly connected to the mounting portion. Consequently, the closed cavity in the apparatus is effectively sealed from the atmosphere and contaminants cannot enter the closed cavity and create premature failure of the component therein, such as, for example, an electrical coil.”
U.S. Pat. No. 6,545,583 discloses a “sealing mechanism [that] comprises a cap and a grommet for sealing an electrical lead extended from a coil overmold or a closed cavity. The grommet provides a first seal against the electrical lead and a second seal against a mounting section around the electrical lead. The cap is snap-fit onto the mounting portion for the lead through engagement between corresponding snap structures on the cap and mounting portion. The grommet comprises a skirt section and a cover section. The skirt section forms a radial seal against the mounting portion while the cover section seals against the leads.”
U.S. Pat. No. 6,737,947 discloses an “electrical assembly that prevents contaminants from migrating to the coil windings within an encapsulant forming the main housing through the use of a sealing assembly located within an over-molded, thermoplastic encapsulant. Before over-molding, an elastomeric seal is installed on each lead wire to be sealed, and this wire/seal subassembly is then inserted into a seal housing made from the same basic thermoplastic as the encapsulant forming the housing. The seal housing has one or more continuous ribs, with sharp edges, that circumvent the outer surface of the seal housing. During over-molding to form the main housing, the molten encapsulant surrounds the seal housing and melts the tips of the ribs. Upon cooling, the (no thermoplastic solidifies and the encapsulant bonds to the seal housing along each of its ribs.”
U.S. Pat. No. 7,151,427 discloses a “switchgear, especially for actuating valves, includes a housing (18) and a coil body (10) disposed in the housing. A switch element is guided in the coil body. The coil body is provided with a winding (14) of a conductor (16) that is connected to a plug connector (22) via contact elements (20). At least some sections of the housing (18) and of the plug connector (22) are enclosed by a plastic compound (24). Sealing devices (40) seal off the interior (42) of the switchgear from the surroundings (44). At least one of the sealing devices (40) is configured as a sealing web (48) of a meltable material. The sealing web (48) is disposed on the bottom face (50) of a plug plate (26) of the plug connector (22) which faces the housing (18). The sealing web (48), in the molten connection state, seals off at least the engaging parts of the plug connector (22) that are connected to the housing (18) from the surroundings (44) in a fluid-tight manner by the plastic compound (24), thereby eliminating the need for conventional rubber packing rings (O rings) in the area of the plug connector that are prone to failures.”
U.S. Patent No. Application Publication No. 20020175791 discloses a solenoid “that has a fully enclosing yoke with integral end cap and sleeve. A second, separate, or alternatively integral end cap with sleeve is provided to complete the magnetic yoke. The yoke/coil assembly is encapsulated with a liquid crystal polymer that has a melting temperature higher than the melting temperature of the coil bobbin to provide a good bond therebetween.”
The inventions disclosed and taught herein are directed to an improved system and method for sealing coil leads during encapsulation.